This invention relates to telephone service over a cable network.
For many years, telecommunication service in the United States has been offered primarily through a network having wire pairs extending to customer homes. More recently, cellular telephony has taken off, and efforts are being made to similarly expand the telecommunication offerings through hybrid fiber-coax cable (HFC).
U.S. Pat. No. 6,236,653 describes an illustrative system, not unlike the one depicted in FIGS. 1 and 2, that provides telephone service through a cable network, as well as Internet service through the cable network. In FIG. 1, a fiber-coax cable 100 extends from head-end station 110 to a plurality of customers, such as customers 200 and 300, which tap into the cable. Cable 100 is representative of an entire network of cables that extend from head-end station 110. Station 110 obtains television signals from some source (for example, the antenna depicted with station 110), modulates those signals into preselected frequency bands, and forwards the signals downstream by means of HFC cable 100. Within a customer's premises, cable 100 signal is received in a set-top box, such as box 210, the set-top box demodulates the received signal in accordance with instructions provided to box 210 by a user, resulting in a specific channel (frequency band) being applied to television monitor 170 at the frequency band to which the tuner within television 170 is set. Thus the user receives a television signal from the specific channel. This is, basically, a one-way broadcast communication arrangement, from head-end 110 to all of the customers on cable 100.
Internet service is provided to PC 150 of customer 200 by interposing cable modem 220 between cable 100 and PC 150. To accommodate such a service, cable 100 and head-end 110 must be adapted to allow two-way communication between the PCs of the various customers that are connected to cable 100 and possess a cable modem, and head end 110 or, more specifically, a data point-of-presence (POP) 120 that is connected to head-end station 110. Relative to Internet service, POP 120 may be an Internet Service Provider (ISP) that is connected to the Internet. Information flows between POP 120 and cable modem 220 in IP packets that, while flowing through cable 100, are modulated onto a carrier.
Telephony service is provided also through cable modem 220, head-end station 110, and POP 120, by carrying the service also through IP packets that flow through cable 110. Thus, modem 220 is more than just a cable modem because it is adapted to handle telephone signals, and POP 120 is more than just an ISP because it is adapted to be connected to local switch 140 of the PSTN, through packet gateway 130, which converts between the analog signals of switch 140 and the IP packets signals of POP 120.
FIG. 2 depicts the structure of cable modem 220, essentially as illustrated in the aforementioned U.S. Pat. No. 6,236,653 patent. Viewed macroscopically, it includes Internet module 700 and a telephony module 600. In module 700, tuner 760 receives signals in the frequency band devoted to IP packet communication and applies its received signal to demodulator 735, which demodulates the received signal to recover a sequence of received TCP/IP or UDP/IP frames and applies them to framer 730. The latter provides a stream of packets to CPU 725, which is a stored-program controller with associated memory 705. CPU 725 provides timing, synchronization and error handling controls to framer 730. CPU 725 also provides IP packets to PC 150 via interface 745. In the upstream direction, packets from PC 150 are applied to framer 730 via interface 745 and CPU 725, and thence to transmitter 740, which provides error correction/detection coding such as Reed-Solomon coding and forms a modulated intermediate frequency (IF) carrier signal. The IF signal is applied to radio frequency (RF) modulator 750, which up-modulates its input signal to the proper frequency bands and forwards the modulated signal to cable 100. Thus, a path is provided for IP packets to flow back and forth between PC 150 and POP 120.
Telephony module 600 comprises a controller that is composed of digital signal processor (DSP) 620 and associated memory 625. The module further comprises analog-digital converter 610, and subscriber-line-interface-circuit (SLIC) 605. The controller performs all of the necessary control telephony functions, converter 610 provides the interface between the digital signals of DSP 620 and the analog signals of SLIC 605 and telephone 160, and SLIC 605 provides the tip/ring interface to telephone 160, such as the ability to sense off-hook, provide loop current, provide dial tone, detect dialing (pulse or DTMF), provide a ringing signal, etc. DSP 620 is coupled to CPU 725 to provide a two-way communication path of digitized telephony signals (IP packets) between telephone 160 and cable 100.
Perusing U.S. Pat. No. 6,236,653 may provide additional insights.
The above described arrangement provides telephony service for telephone 160, digital communication (Internet) service for PC 150 (which has computing capability as well as audio and video capability), and entertainment programming service for TV 170 (which also has audio and video capability)—but all of these services are independent, and do not commingle. We realized that an advance in the art can be attained by allowing these to commingle.
In a related art, U.S. Pat. No. 5,566,231 describes an arrangement for enhancing a customer premises message-recoding device. The enhanced recording device has the ability to store caller ID information arriving from the telephone network in association with the incoming call that is recorded, as well the ability to ascertain the call duration and other information. This information is stored in association with the stored message. Through a remote controller that connects to the enhanced recording device through an IR link, a user can retrieve the stored messages and the stored associated information. To display the retrieved information, the conventional cable-TV connection between the set-top box and the TV monitor is looped through the enhanced recorder, and the retrieved information is displayed on the TV monitor though a video interface connector that is connected to the TV monitor.
What the U.S. Pat. No. 5,566,231 patent suggests is the notion of storing caller ID and other data that is provided by the telecommunication network in association with an incoming call that is recorded, so that thereafter, the information is retrieved by a user and displayed by the user on a TV monitor. However, the patent does not teach how the incoming information is modified to a format suitable for a television monitor, or how the video interface connector interacts with the cable from the set-top box to inject its signal so that it may be displayed on the TV monitor. Moreover, the arrangement is not interactive, in the sense that the enhanced recording device stores information, but the user can only retrieve it. The user cannot control the call progress, or any other interaction with the telecommunication network, based on real time information obtained from the TV monitor.